Atomic-scale structure relaxation, chemistry and charge distribution of dislocation cores in SrTiO₃

By using the state-of-the-art microscopy and spectroscopy in aberration-corrected scanning transmission electron microscopes, we determine the atomic arrangements, occupancy, elemental distribution, and the electronic structures of dislocation cores in the 10° tilted SrTiO₃ bicrystal. We identify that there are two different types of oxygen deficient dislocation cores, i.e., the SrO plane terminated Sr_0.82Ti_0.85O_3-x (Ti^3.67+, 0.48 ≤ x ≤ 0.91) and TiO₂ plane terminated Sr_0.63Ti_0.90O_3-y (Ti^3.60+, 0.57 ≤ y ≤ 1). They have the same Burgers vector of a[100] but different atomic arrangements and chemical properties. Besides the oxygen vacancies, Sr vacancies and rocksalt-like titanium oxide reconstruction are also identified in the dislocation core with TiO₂ plane termination. Our atomic-scale study reveals the true atomic structures and chemistry of individual dislocation cores, providing useful insights into understanding the properties of dislocations and grain boundaries.